Brush seals provide a technology for sealing high pressure areas from low pressure areas, for example, areas associated with gas turbine engines. Typically, brush seals inhibit the flow of a gas or liquid in a stream along a shaft.
Some brush seal applications involve very high temperatures, which can produce non-uniform thermal growth among associated components. For instance, many engine parts experience significantly higher temperatures during take-off, only to later be reduced during normal operation or equilibrium. Thermal gradient and thermal expansion differences can cause non-uniform thermal growth among various engine parts. Under such conditions, some brush seals have to work with a reduced gap or with an interference fit with respect to a rotating shaft. Another potential drawback associated with prior art brush seals is their tendency to enter into a vicious cycle once the bristles experience heavy contact with the rotating shaft. With conventional brush seals, one end of the bristle is typically attached (either by welding or mechanical clamping) to the seal housing and the seal housing is pressed into seal carrier of the surrounding structural components. The heat generated by the rubbing between the bristles and shaft commonly leads them to grow more and more into each other, which in turn results in more interference and heavier rubbing until heavy wear of bristles reduces the associated interference. Those conditions can increase or accelerate the wear on the brush seal and degradation of the surface of an associated shaft. Consequently, a brush seal that, among other things, helps to address the conditions associated with temperature gradient and thermal expansion differences is desirable.